Chemical Elements, Compounds, and Mixtures

Question 1

Elements

Answer 1

Substances made from one kind of atom

Question 2

Compounds

Answer 2

Made from two or more elements chemically combined

Question 3

Mixture

Answer 3

Elements and compounds are interspersed with each other, but are not chemically combined (meaning that the component substances retain their pure form characteristics)

Question 5

Homogeneous mixture

Answer 5

Uniform composition and properties throughout

Question 6

Heterogeneous mixture

Answer 6

Non-uniform composition, properties are not the same throughout

Question 7

Separating Techniques

Answer 7

The choice of the method depends on the nature of the substances being separated, and all rely on there being a difference if some sort, usually in physical property

Question 8

How can solids be separated

Answer 8

Difference in solubility, a suitable solvent must be chosen so that only the desired substance dissolves in it and no other substances or impurities do (eg. to separate salt and sand, water is a suitable solvent for salt but not sand)

Question 9

Filtration

Answer 9

Used to separate an undissolved solid from a mixture of solid and a liquid

Question 10

Crystallization

Answer 10

Used to separate a dissolved solid from a solution, when the solution is more soluble in a hot solvent than in cold

Question 11

Recrystallization

Answer 11

Used to purify impure solids;a hot solvent is used to dissolve both the organic solid and the impurities and then as the solution cools,then the solid crystallizes out and leaves behind the impurities in the solution

Question 12

Simple Distillation

Answer 12

Used to separate a liquid and soluble solid from a solution or a pure liquid from a mixture of liquids; 1) the solution is heated and pure water evaporates producing a vapor which rises through the neck of the found-bottomed flask, 2) the vapor passes through the condenser, where it cools and condenses, turning into pure water, 3) after all water has evaporated, the solid solute will be left behind

Question 13

Fractional Distillation

Answer 13

Used to separate two or more liquids that are miscible with one another; it’s done with substances that have different boiling points so that when the solution is heated, the lower boiling point substance will evaporate, pass through a condenser, and then be collected in a beaker. The other components (with the higher BP) will be left in the beaker.

Question 14

Paper Chromatography

Answer 14

Used to separate substances with different solubilities in a given solvent.

Question 15

Solids

Answer 15

Fixed volume and shape, high density, atoms vibrate in position but cannot move, particles are packed very closely together in a regular pattern

Question 16

Liquids

Answer 16

Fixed volume, adopt the shape of the container, less dense than solids, more dense than gases, particles move and slide past each other which is why they adopt the shape of the container and why they are able to flow freely

Question 17

Gases

Answer 17

Do not have fixed volume, take shape of container but fill the whole container, very low density, because of the space between particles, gases can be compressed into much smaller volumes, particles are far apart and move quickly and randomly in all directions, once they collide with each other and the walls of the container pressure is made

Question 18

Sublimation

Answer 18

Solid ——> gas

Question 19

Deposition

Answer 19

Gas——-> solid

Question 20

Melting

Answer 20

Solid ——-> liquid

Question 21

Freezing

Answer 21

Liquid ——-> solid

Question 22

Vaporizing

Answer 22

Liquid ——-> gas

Question 23

Condensing

Answer 23

Gas ———> liquid

Question 24

To break bonds…

Answer 24

Energy is always needed to overcome the forces of attraction between particles